1. Field of the Invention
The present invention relates to a pump; and more particularly relates to a technique for controlling power to a pump in a liquid dispensing system.
2. Brief Description of Related Art
In the prior art, a conventional bottled water system includes a DC pump and mechanical pressure switch that shuts off the pump when certain pressure (i.e., the shut-off pressure) is exceeded. This pressure switch is typically connected in series with the transformer secondary winding; and the transformer is used to scale down the line voltage to the pump operation voltages. During the pump off condition, the transformer is still powered up, which leads to a power loss in the transformer and heating of the transformer, e.g., the transformer can typically be heated to about 120° F. and draws current constantly. Another issue relates to the motor inrush at the startup, which demands that a higher size transformer to be used.
Units are also known in the art that have a base unit that contains a pump and several electrical components internally installed. The base unit has an integral hose with a wand that is inserted into a bottled water container and draws the water into the pump. The outlet of the system is usually restricted down to be connected to an appliance such as a drink machine, refrigerator or similar appliance. With integral hoses fixed in place, any damage to these hoses requires either extensive rework or purchase of a new unit. The electronics are simple components with no filtering or protection of the circuits. This design also requires multiple models to accommodate different voltages used in the markets. Various models are required due to the units being hardwired with power cords to accommodate the numerous voltages and plugs used in the markets.
By way of example, FIGS. 1a and 1b are an illustration of a bottled water pump system disclosed in U.S. patent application Ser. No. 12/251,160, filed 14 Oct. 2008 (ITT/WFVA file nos. 07JAB003//911-12.17-2), which is hereby incorporated by reference in its entirety. The bottled water pump system features a dispenser or dispensing system configured to provide fluid from multiple reservoirs to an appliance or other suitable device; and a multiple tubing arrangement configured to couple the dispenser system and the multiple reservoirs of fluid. In operation, the multiple tubing arrangement are configured to respond to a vacuum provided from the dispenser system, and draw the fluid from the multiple reservoirs to the appliance, so as to deplete the multiple reservoirs at relatively equal amounts based on the Venturi effect.
Moreover, switched-mode power supply technology (also known as switching-mode power supply, SMPS, or simply switcher) is known in the art, and may take the form of an electronic power supply that incorporates a switching regulator in order to be highly efficient in the conversion of electrical power. Like other types of power supplies, an SMPS transfers power from a source like the electrical power grid to a load (e.g., a personal computer) while converting voltage and current characteristics. An SMPS is usually employed to provide a regulated output voltage, typically at a level different from the input voltage. Unlike a linear power supply, the pass transistor of an SMPS switches quickly (typically between 50 kHz and 1 MHz) between full-on and full-off states, which minimizes wasted energy. Voltage regulation is provided by varying the ratio of on to off time. In contrast, a linear power supply must dissipate the excess voltage to regulate the output. This higher efficiency is the chief advantage of an SMPS.